def number_pattern(n):
    if not isinstance(n, int):
        return 'Argument must be an integer value.'
    if n < 1:
        return 'Argument must be an integer greater than 0.'
    pattern = ''
    for i in range(1, n+1):
        pattern += str(i) + ' '
    return pattern.rstrip()

if __name__ == '__main__':
    print(number_pattern(4))